Kalendae, Nonae, Idus

A very early attempt of dividing the time elapsed between the cyclic changing of the seasons was a 10-month year, whose total length was 304 days. This scheme, probably already in use by the time of Rome's foundation, was obviously inaccurate; for this reason, an uncounted number of days was likely added, so that events for which a specific timing was required, such as sowing or gathering the harvest, could be carried out reasonably on time.

The second roman king, Numa Pompilius (c.700 BC), is traditionally credited for having increased the number of months by two, thus lengthening the year to 355 days. Having this scheme been adopted also by the following Republican Age, up to the 1st century BC, it is now usually referred to as the roman Republican year.

This year originally started with the month of March (New Year's Day fell on March 14), probably because early spring is the period in which nature comes to new life again after the cold season. January and February, recently added, were infact the last months of the year.
Part of the twelve months had names that recalled the gods whom they were sacred to, while others were named after their ordering sequence:

REPUBLICAN YEAR		PRESENT SYSTEM
MONTH	DEDICATION^✶ OR MEANING	LENGTH	MONTH	LENGTH
*Martius*	Mars - god of war	31 days	March	31 days
*Aprilis*	Venus (Greek: Aphrodite) - goddess of beauty and love; maybe also after verb aperire, "to open", referring to the unfolding of buds in spring	29 days	April	30 days
*Maius*	Maia - one of the seven Pleiades	31 days	May	31 days
*Iunius*	Juno - queen of all gods	29 days	June	30 days
*Quintilis*	the fifth month	31 days	July	30 days
*Sextilis*	the sixth month	29 days	August	31 days
*September*	the seventh month	29 days	September	30 days
*October*	the eighth month	31 days	October	31 days
*November*	the ninth month	29 days	November	30 days
*December*	the tenth month	29 days	December	31 days
*Ianuarius*	Janus - god of gates and beginnings	29 days	January	31 days
*Februarius*	Februus - minor roman god, later identified with Pluto, ruler of the infernal regions	28 days	February	28 days
	*Total length of the year :*	355 days		365 days

The fifth roman king, Tarquinius Priscius (c.600 BC) decided that January should have been the opening month of the year, because sacred to the god of all beginnings. But this change did not last long: when the Etruscan dynasty he belonged to was dismissed about one century later, March became again the first month, according to Latin tradition. The 355-day system, though, kept causing a certain mismatch between different years, due to its short duration, and the problem was coped with by adopting a thirteenth month, named Intercalans ("intercalary month") or Mercedonius ("month of wages", because by this time of the year workers received their payment); its length was either 27 or 28 days. About once every two years, the additional month was inserted between February 23rd and 24th, and the five remaining days of the month were cancelled. The pontefices, religious officers who presided over rites, decided when the Intercalans had to be adopted, and how long it would have lasted. Despite the additional month, though, this system was still not too precise, and the occasional corruption of the pontefices to lengthen or shorten the year (according to the briber's needs) had several legal implications: for example, a contract's expiry date could have been illegally postponed.	the pontefices were in charge for dating systems

Julius Caesar	*THE JULIAN CALENDAR* An important modification was introduced by Julius Caesar in 46 BC (see table below): the length of some months was rearranged, thus avoiding the Intercalans, and obtaining an alternate duration (30/31 days), an easier scheme to follow by farmers; January was chosen again to be the starting month of the year. Furthermore, having Caesar's astronomers realized that the actual solar year was slightly longer than 365 days, every four years February (already lengthened to 29 standard days) was given one more day, by repeating the 24th: this was the birth of the leap year. The reformed system was named Julian calendar, after Julius Caesar; for the same reason, in 44 BC the month of Quintilis was renamed Iulius, in his honour.

the Republican calendar, on the left, compared to the Julian one (before and after Ottavianus' alteration): all years highlighted are leap years	Towards the end of the 1st century BC, Octavianus Augustus, Rome's first emperor, changed the name Sextilis into Augustus, lengthening it to 31 days, probably because 'his' own month had fewer days than Caesar's own. Not to alter the total number of days in the year, the emperor rearranged the length of other months; the result was the same calendar we currently use (see table on the left, right column). Since February 24th was referred to as ante diem sextum Kalendas Martias ("the sixth day before the Kalendae of March", see DAYS AND WEEKS, further in the page), leap years were named bissexti anni ("years with a double 24th").

The Julian calendar was adopted by the whole western world, and used throughout Rome's Imperial Age, and the Middle Age.

*THE GREGORIAN CALENDAR* Only by the 16th century, astronomers realized that since the solar year did not exactly match the length of 365 + ¼ days, the Julian calendar had been running slightly slow for the past sixteen centuries, losing about ten days. In 1582 AD, pope Gregory XIII had a correction made, and filled the gap by simply skipping this delay: October 4th was directly followed by October 15th, which means that all days between these two dates did never really exist. To prevent similar situations in the future a new rule was introduced, by which centennial years would have been leap years only when their first two digits could have been divided exactly by 4 (this is the case of 1600 and 2000, while 1700, 1800 and 1900 were not leap years).	Gregory XIII (1572-85)

THE GREGORIAN CALENDAR

Only by the 16th century, astronomers realized that since the solar year did not exactly match the length of 365 + ¼ days, the Julian calendar had been running slightly slow for the past sixteen centuries, losing about ten days.
In 1582 AD, pope Gregory XIII had a correction made, and filled the gap by simply skipping this delay: October 4th was directly followed by October 15th, which means that all days between these two dates did never really exist.
To prevent similar situations in the future a new rule was introduced, by which centennial years would have been leap years only when their first two digits could have been divided exactly by 4 (this is the case of 1600 and 2000, while 1700, 1800 and 1900 were not leap years).

Gregory XIII
(1572-85)

Counting years, instead, was a later achievement than keeping an account of months.
The need of a common parameter for locating major events in time, such as the building of a temple, a birth date or a death date, etc., came probably during Rome's Republican age: scholars realized that a better way than referring to past events simply as "happened a long time ago" had to be adopted.
Two parallel systems were then introduced.

The first one was based on counting years from Rome's foundation, a criterion which was highly speculative, due to the uncertain reference, until the most important roman scholar, Marcus Terentius Varro (1st century BC), defined the foundation date of Rome to be year 753 BC. Not long after, the above-said date was slightly corrected to year 754; however, the first dating is presently reputed more likely by the majority of scholars. In official spellings, these dates were often followed by the three letters A.U.C., for ab Urbe condita ("since the City was founded").
Obviously, romans did not think of this date in terms of 753 BC, but as year 1; for instance, 100 BC would have been year 653 A.U.C., and year 1492 AD would have been 2245 ab Urbe condita.
Only by the 6th century AD, in the early Middle Age, Christian culture affected the dating system, and years began to be recorded as from Christ's birth, i.e. AD (Latin Anno Domini, "in the year of the Lord").

The second criterion was to mention the name of the consul (high magistrate) in charge, or of the victorious general celebrated by the time a certain event had taken place. In fact, consuls were appointed in March (first month of the Republican calendar), and the year itself was usually named either after the consul, or after a general whose victorious campaign was publicly celebrated (a ceremony known as "triumph"). Stone plates called fasti consulares or fasti triumphales, according to their reference, officially marked each day of the year, also mentioning the main public events (religious celebrations, sport competitions, etc.) held over the relevant period.		the Fasti hung by the Arch of Augustus, in the Roman Forum, listed the names of all consuls and victorious generals, up to the early empire

menologium rusticum for July, August and September	Besides the fasti, other types of calendars were also used: the feriali, similar to the fasti, but only containing the festivities of the given period; the menologii rustici were tables covering three months (i.e. a season), used for agricultural purposes, since they mentioned the number of days each month had, on which day the Nonae fell (see below), the zodiac sign, the god or goddess whom the month was dedicated to, the main farming duties to be carried out, the main festivities, etc.; nundinal or market calendars (see below, DAYS AND WEEKS); astrological calendars, a sample of which is shown in the following paragraph, featured the zodiac signs and were used for knowing the position of the planets.

menologium rusticum for
July, August and September

Besides the fasti, other types of calendars were also used:

the feriali, similar to the fasti, but only containing the festivities of the given period;

the menologii rustici were tables covering three months (i.e. a season), used for agricultural purposes, since they mentioned the number of days each month had, on which day the Nonae fell (see below), the zodiac sign, the god or goddess whom the month was dedicated to, the main farming duties to be carried out, the main festivities, etc.;

nundinal or market calendars (see below, DAYS AND WEEKS);

astrological calendars, a sample of which is shown in the following paragraph, featured the zodiac signs and were used for knowing the position of the planets.

a nundinal calendar, showing market days for several cities (list on the right), including Rome	DAYS AND WEEKS In Rome's early centuries, a common way for measuring short lengths of time was the nundinum: this word literally meant "9-day period", since a market was held in the main cities and towns every ninth day. The actual length of this period, though, was eight days, because romans used the so-called "inclusive numbering", a criterion by which the last unit of a series was also considered the first unit of the following series: therefore, the nundinae (i.e. the actual market days) were both the last day of one nundinum and the first day of the following period, as shown below.

a nundinal calendar, showing market days
for several cities (list on the right), including Rome

DAYS AND WEEKS

In Rome's early centuries, a common way for measuring short lengths of time was the nundinum: this word literally meant "9-day period", since a market was held in the main cities and towns every ninth day. The actual length of this period, though, was eight days, because romans used the so-called "inclusive numbering", a criterion by which the last unit of a series was also considered the first unit of the following series: therefore, the nundinae (i.e. the actual market days) were both the last day of one nundinum and the first day of the following period, as shown below.

In fasti calendars, the days of the nundinum were indicated with letters of the Latin alphabet, from A to H. Furthermore, all days of the year were classified by the pontefices, on the basis of divinations and predictions, as any of the following five types: fasti (favourable), marked "F"; nefasti (unfavourable), marked "N"; comitiales (assembly days), marked "C"; endotercisi (whose central part was favourable, but started and finished as unfavourable days), marked "EN"; days marked "NP", whose meaning is still obscure; all the Idus days (see below) and the festivities belonged to this type.	detail (July to December) of a fasti calendar of years 20-23 AD: the first letter tells the nundinal day, followed by the type of day, and the third column reports celebrations, games, or other activities

In fasti calendars, the days of the nundinum were indicated with letters of the Latin alphabet, from A to H.
Furthermore, all days of the year were classified by the pontefices, on the basis of divinations and predictions, as any of the following five types:

fasti (favourable), marked "F";
nefasti (unfavourable), marked "N";
comitiales (assembly days), marked "C";
endotercisi (whose central part was favourable, but started and finished as unfavourable days), marked "EN";
days marked "NP", whose meaning is still obscure; all the Idus days (see below) and the festivities belonged to this type.

detail (July to December) of a fasti calendar of years 20-23 AD:
the first letter tells the nundinal day, followed by the type of day,
and the third column reports celebrations, games, or other activities

Any public activity could be carried out only on the fasti and comitiales days, and during the central part of the endotercisi days, but not at the beginning nor at the end of the latter, nor at any time during the nefasti days.

detail of the Fasti Praenestini (early 1st century BC), covering one full nundinum, from A to H	Besides the nundinal day and the type of day, an average fasti calendar also featured the three main reference days of the month, K (Kalendae), NON (Nonae), EID (Eidus) , spelt in large letters, or small roman numerals which referred to the count of the days ahead of the next reference to come (see below for a full description), and also the names of major festivities and celebrations, as shown in the following detail. When additional days were introduced by Julius Caesar's reformation, they were all added at the end of the respective months, and designated as fasti, not to cause further complications.

detail of the Fasti Praenestini
(early 1st century BC),
covering one full nundinum, from A to H

Besides the nundinal day and the type of day, an average fasti calendar also featured the three main reference days of the month, K (Kalendae), NON (Nonae), EID (Eidus) , spelt in large letters, or small roman numerals which referred to the count of the days ahead of the next reference to come (see below for a full description), and also the names of major festivities and celebrations, as shown in the following detail.

When additional days were introduced by Julius Caesar's reformation, they were all added at the end of the respective months, and designated as fasti, not to cause further complications.

Meanwhile, the Jews (taken to Rome as slaves from Palestine) followed a lunar calendar by which cycles of 28 days were divided into four 7-day periods. Gradually, romans too started indicating days by giving them seven different names. This became a well established custom by the 1st century BC, although the concept of "week" as a given entity of time was only to come in the 4th century AD under emperor Constantine the Great.
The Latin names of week days were chosen after the planets known by those times (according to the Ptolemaic system, they were all believed to revolve around Earth, including the Sun):

LATIN NAME	MEANING	ENGLISH NAME
*dies Saturni*	day of Saturn	Saturday
*dies Solis*	day of the Sun	Sunday
*dies Lunae*	day of the Moon	Monday
*dies Martis*	day of Mars	Tuesday
*dies Mercurii*	day of Mercury	Wednesday
*dies Iovis*	day od Jupiter	Thursday
*dies Veneris*	day of Venus	Friday

Note that the roman week started in coincidence with the Jewish holiday of Shabbath, the biblical "7th day" on which God had rested, thus believers were not allowed to perform any kind of activity on this day. Romans were pagan, and did not rest on Saturdays, although their dies Saturnii matched the Jewish festivity, what can be told by the alternative Latin name of this day, dies Sabbati ("day of the Shabbath").
Only several centuries later, when Rome's leading religion was already Christian, Sunday became the official holiday of the week, was renamed dies Dominicus ("day of the Lord"), and replaced the Jewish Saturday.

astrological calendar with the days of the week in the shape
of gods, each of which identifiable by a symbolic features:

- Saturn (beard and sickle)
- Sun (rays)
- Diana (moon crescent)
- Mars (spear and helmet)
- Mercury (winged helmet and medical staff)
- Jupiter (beard and thunderbolts)
- Venus (female with a fancy hair-style)

The most amazing feature of Rome's calendar system, though, was how days were calculated within each month. In fact, they were not simply numbered, as we do nowadays, requiring rather unpractical calculations.
Each month had three "fixed days", which bore a specific name:

Kalendae, the 1st day of all months
Nonae, the 5th day (but the 7th day in March, May, July and October)
Idus or Eidus, the 13th day (but the 15th day in March, May, July and October)

The meaning of Nonae is actually "the ninth day before the Idus", which should be counted keeping in mind the roman inclusive numbering criterion (i.e. we would now consider this as the eighth day before the Idus).
The name Idus (Eidus), instead, comes from the verb iduare, "to divide", thus meaning "the central day of each month".

The days immediately before and after the above-said dates were called their pridie and postridie, respectively. All others were referred to as the number of days before the following fixed ones, by using the complicated expression ante diem + the number of missing days + the following fixed date.
For example, September 9th would have been ante diem quintum Idus Septembres ("fifth day before September's Idus"), in short form: A.D. V ID. SEP.
Another example is May 25th, which would have been ante diem octavum Kalendas Iunias ("eighth day before June's Kalendae"), in short: A.D. VIII KAL. IUN., and so on.
The postridie form was not used as much as the pridie, so the general ante diem form would often take its place: December 6th could have been spelled postridie Nonas Decembres ("the day following December's Nonae"), but it could have more often been mentioned as ante diem octavum Idus Decembres ("eighth day before December's Idus"), in short: A.D. VIII ID. DEC.

The following table shows the calendar of a full roman imperial year (Julian calendar, after Ottavianus' alterations).

LINGUISTIC NOTE In naming days, after the expressions pridie, postridie and ante diem, the feminine plural nouns Kalendae, Nonae and Idus required the accusative case (Kalendas, Nonas, Idus), while they were used in ablative case (Kalendis, Nonis, Idibus) on their own "fixed day".
These nouns were then followed by the name of the month, used as an actual adjective, matching gender, number and case of the "fixed day" (i.e. feminine plural, in accusative or ablative case).

The old calendar system died out through the Middle Ages. One of its latest specimens can be seen by an ancient church in Rome, called Santi Quattro Coronati, where a hall leading to the church's nunnery has walls covered with 13th century paintings (right), still partly visible, featuring a religious calendar in which the days are marked with letters from A to H, calculated in terms of Kalendae, Nonae and Idus, but in place of the pagan festivities listed in the old fasti, the names of the saint to whom each day was dedicated can be read on the relevant line.	painted religious calendar (13th c.), by the church of Santi Quattro Coronati

The old calendar system died out through the Middle Ages. One of its latest specimens can be seen by an ancient church in Rome, called Santi Quattro Coronati, where a hall leading to the church's nunnery has walls covered with 13th century paintings (right), still partly visible, featuring a religious calendar in which the days are marked with letters from A to H, calculated in terms of Kalendae, Nonae and Idus, but in place of the pagan festivities listed in the old fasti, the names of the saint to whom each day was dedicated can be read on the relevant line.

painted religious calendar (13th c.), by the church of Santi Quattro Coronati

this page was created on
PRIDIE KALENDAS MARTIAS � ANNO MMDCCLIII AB URBE CONDITA
(February 29th 2000)